Futures linked to the major stock gauges all slumped Sunday night as tariff uncertainty dragged on market optimism.

Investors reacted to the Federal Reserve's decision to leave rates unchanged, by handing the S&P 500 its biggest percentage gain for a Fed day since last July. The Nasdaq Composite had its best Fed day since Nov.

U.S. stocks saw a selloffi accelerate on slightly hotter-than-expected inflation data and ongoing tariff worries that could keep Fed rates on hold.